Ernst Paul Specker (11 February 1920, Zürich – 10 December 2011, Zürich) was a Swiss mathematician. Much of his most influential work was on Quine's New Foundations, a set theory with a universal set, but he is most famous for the Kochen–Specker theorem in quantum mechanics, showing that certain types of hidden variable theories are impossible. He also proved the ordinal partition relation ω² → (ω²,3)², thereby solving a problem of Erdős.

Specker received his Ph.D. in 1949 from ETH Zurich,^[1] where he remained throughout his professional career.